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CVE-2026-40192

HIGH
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-04-13 https://github.com/python-pillow/Pillow GHSA-whj4-6x5x-4v2j
Denial Of Service
8.7
CVSS 4.0 · Vendor: https://github.com/python-pillow/Pillow
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Severity by source

Vendor (https://github.com/python-pillow/Pillow) PRIMARY
8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (https://github.com/python-pillow/Pillow).

CVSS VectorVendor: https://github.com/python-pillow/Pillow

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

7
PoC Detected
Apr 22, 2026 - 20:08 vuln.today
Public exploit code
Re-analysis Queued
Apr 15, 2026 - 23:22 vuln.today
cvss_changed
CVSS changed
Apr 15, 2026 - 23:22 NVD
8.7 (HIGH)
Analysis Generated
Apr 15, 2026 - 12:34 vuln.today
Analysis Generated
Apr 13, 2026 - 19:30 vuln.today
Patch released
Apr 13, 2026 - 19:30 nvd
Patch available
CVE Published
Apr 13, 2026 - 19:22 nvd
HIGH 8.7

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 331 pypi packages depend on pillow (276 direct, 59 indirect)

Ecosystem-wide dependent count for version 10.3.0.

DescriptionCVE.org

Impact

Pillow did not limit the amount of GZIP-compressed data read when decoding a FITS image, making it vulnerable to decompression bomb attacks. A specially crafted FITS file could cause unbounded memory consumption, leading to denial of service (OOM crash or severe performance degradation).

Patches

The amount of data read is now limited to the necessary amount. Fixed in Pillow 12.2.0 (PR #9521).

Workarounds

Avoid Pillow >= 10.3.0, < 12.2.0 Only open specific image formats, excluding FITS.

AnalysisAI

Unbounded GZIP decompression in Pillow's FITS image parser enables remote denial-of-service via crafted image files. Pillow versions 10.3.0 through 12.1.x process FITS images without limiting decompression output, allowing attackers to trigger out-of-memory crashes or severe performance degradation through maliciously compressed images. Vendor-released patch available in Pillow 12.2.0. No active exploitation confirmed (not in CISA KEV), but the attack vector is trivial for any application accept

Technical ContextAI

Pillow is Python's de facto image processing library (pkg:pip/pillow), supporting over 30 file formats including FITS (Flexible Image Transport System), an astronomy data format with GZIP compression support. The vulnerability stems from CWE-770 (Allocation of Resources Without Limits or Throttling) in the FITS decoder introduced in version 10.3.0. When parsing FITS files, the library decompresses embedded GZIP streams without size validation, creating a classic decompression bomb scenario where attackers embed minimal compressed data that expands to gigabytes in memory. Unlike image dimension-based bombs (which Pillow guards against), this exploits the decompression layer before image data is validated. The fix (PR #9521, commit 3cb854e) enforces decompression output limits proportional to declared FITS image dimensions, mirroring protections already present for other compressed formats like PNG.

RemediationAI

Upgrade Pillow to version 12.2.0 or later immediately using pip install --upgrade pillow==12.2.0 or equivalent package manager commands. The fix (PR #9521, commit 3cb854e8b2bab43f40e342e665f9340d861aa628) enforces decompression output limits proportional to image metadata. For environments unable to upgrade immediately, implement one of two workarounds: (1) Pin Pillow to version 10.2.0 or earlier (pre-regression), though this forgoes 21 months of other security fixes, or (2) configure Pillow's Image.open() with the formats parameter to explicitly exclude FITS, as documented at https://pillow.readthedocs.io/en/stable/releasenotes/8.0.0.html#image-open-add-formats-parameter (example: Image.open(file, formats=['PNG', 'JPEG'])). For containerized deployments, rebuild base images with updated Pillow. Verify patch effectiveness by testing with known decompression bomb samples. Release notes: https://pillow.readthedocs.io/en/stable/releasenotes/12.2.0.html#prevent-fits-decompression-bomb.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP7 Fixed
SUSE Linux Enterprise Module for Python 3 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed

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CVE-2026-40192 vulnerability details – vuln.today
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